The present invention relates in general to exhaust extraction systems for emergency vehicles, such as a fire truck or ambulance. More particularly, the present invention relates to the design of a magnetically-attached nozzle which is designed to fit over the exhaust system tail pipe of an emergency vehicle.
Emergency vehicles, such as a fire truck, create an interesting exhaust-removal challenge due to the nature and manner of use of the vehicle in preparation for an emergency run. A fire truck is usually backed into the fire house garage bay and readied for its next run in this manner. When an alarm call comes in, the engine of the fire truck is started by the driver while he waits for everyone to prepare the equipment and get on board. During this brief time interval before the truck leaves the station, exhaust gases are generated and need to be vented to the outside atmosphere.
The exhaust system of a fire truck is typically arranged so that the "tail" pipe exits from the right side of the truck in front of the rear axle. While this location places the exiting exhaust gases near the center of the fire house, it is an advantageous location for present day exhaust extraction systems. For the most part these present day exhaust extraction systems use a flexible exhaust hose which is connected at one end to the fire truck exhaust pipe and at the opposite end to an overhead duct which leads out of the fire house. A high pressure blower is used to forcibly remove the exhaust gases from the fire house. A hose adapter or nozzle assembly of some type is typically used to connect the flexible hose to the exhaust pipe. With secure and sealed connections and so long as there are no perforations or open seams in the exhaust extraction system, all of the vehicle exhaust gases will be safely vented out of the fire house and into the atmosphere.
The use of a flexible hose to remove exhaust gas from a running engine is not new. Automobile mechanics have used such hoses for years. However, there is one important difference between use by a mechanic and use as part of an exhaust extraction system which is attached to an exhaust pipe of a fire truck. Once everyone is onboard the fire truck, it is ready to leave the fire house and there is usually no one left to disconnect the exhaust hose from the exhaust pipe. Even if personnel were left behind, safe handling of the vehicle exhaust would dictate that the vehicle be pulled out of the fire house and then have the hose removed. This would involve a start up and stop procedure at the very time the fire truck is trying to leave quickly on the emergency run. Even if someone was left behind and could disconnect the exhaust hose prior to the fire truck departing, this would allow exhaust gas to be dispersed into the fire house, the very event which exhaust extraction systems are designed to prevent.
In order to address this disconnect concern, present day exhaust extraction systems try to provide an automatic disconnect feature such that the adapter or nozzle connecting the flexible hose to the exhaust pipe comes off automatically after the fire truck has actually left the fire house. While present exhaust extraction systems which are offered commercially have approached this design challenge in slightly different ways, most systems provide an extra length of flexible hose which is suspended from an overhead track. A spring-biased balancer supports the hose and causes the release as the fire truck leaves the station. As the fire truck leaves, the distance between the exhaust pipe and the hose connection to the overhead duct increases. This pulls on the flexible exhaust hose which uncoils and the "surplus" length of hose is used. As the hose uncoils in order to stretch, the balancer uncoils which increases the resisting spring force. At some point, before the hose is completely extended, the resisting spring force of the balancer becomes greater than the force needed to separate the adapter from the exhaust pipe. Continued travel of the fire truck does not pull any more of the hose and the induced force on the adapter causes the hose adapter/nozzle to separate from the exhaust pipe. This occurs before the hose is fully extended which could place tension on the connection between the hose and the overhead duct.
The following companies have offered exhaust extraction systems which for the most part can be said to function in the manner which has been described: Harvey Industries, Inc., 1340 Home Avenue, Buildings F an G, Akron, Ohio 44310-2580; Nederman, Inc., P. O. Box 278, McBee S.C. 29101, Westland, Mich.; Tykron, 241 South Service Road, Grimsby, Ontario L3M1Y7, Canada; Plymovent, 375 Raritan Center Parkway, Edison, N.J. 08837; and Exhaustomatic, Inc., P. O. Box 503444, Indianapolis, Ind. 46250.
While the exhaust extraction systems offered by these listed companies are directed to solving the same problem, and while they can be said to generally perform in the same way, there are various design differences and different features which are offered. The overhead track and duct components, the balancer and the flexible hose are fairly well developed and would be considered as fairly mature technology. The "tail" pipe adapter though is an area of greater design attention. The desire is to provide a design which can be easily and securely attached to the exhaust pipe in order to connect the extraction system and yet release in a predictable and reliable manner without damage to the nozzle adapter, flexible hose or the exhaust pipe or for that matter any other portion of the vehicle or fire house.
The exhaust extraction system of Harvey Industries, Inc., connects the flexible hose to the exhaust pipe by a spring loaded clamp which is mounted on and extends through the nozzle. The nozzle is removed from the exhaust pipe when the balancer resisting spring force overcomes the clamp spring. The nozzle does not provide a seal around the exhaust pipe, but it does permit for ambient air to enter the nozzle.
The exhaust extraction system of Nederman, Inc., provides an electromagnetic attachment where a magnet attaches to the side of the fire truck and holds the nozzle opening at the exhaust pipe height. The nozzle does not provide a seal around the exhaust pipe but it does allow ambient air to enter the nozzle. In those fire station arrangements which use front and rear doors for a pass through bay, this system will not be suitable for that design.
The exhaust extraction system of Tykron uses a nozzle with a tension spring which rests in a groove inside the nozzle and surrounds the exhaust pipe. The nozzle spring does not provide a seal around the exhaust pipe, nor does it allow the maximum amount of air to enter in relation to its inside diameter size.
The exhaust extraction system of Plymovent uses a pneumatic bladder nozzle attachment concept. The bladder has three compartments and provides three points of pressure contact but does not form a complete seal around the exhaust pipe. The pneumatic bladder nozzle allows a very small volume of air to enter, but does not permit the maximum amount of air to enter. Consequently, with respect to the nozzle inside diameter size, this does not allow the complete system to operate at the lowest possible temperature. The described pneumatic system requires an air compressor, air filter and lubricator, air lines, controls, and the pneumatic bladder which adds to the overall cost and complexity of the system. It is believed that air leaks are a problem with this system and further, if the fire truck leaves the station at too fast a speed and the air has not been bled out of the nozzle bladder, the flexible hose can be damaged. Since there is a partial seal on the exhaust pipe, this can cause a two cycle turbocharger on a diesel engine to rotate without lubrication when the exhaust blower operates and all engines connected to the system are not running.
The exhaust extraction system of Exhaustomatic, Inc., actually has four variations as far as securing the nozzle to the exhaust pipe. Their product literature indicates that the four nozzle designs include a clamp design, permanent magnet design, electromagnetic design, and a pneumatic design. It is believed though that in these designs the nozzle does not provide a complete seal on the exhaust pipe. However, these designs do allow ambient air to enter and provide some system cooling, except when the pneumatic nozzle is used.
The present invention differs from these earlier designs in a number of novel and unobvious ways. The focus of the present invention is on two cooperating parts, the hose nozzle and a nozzle locator ring which connects to the exhaust pipe of the fire truck. While some preliminary work may need to be done to the exhaust pipe for connection to the nozzle locator ring, the invention novelty resides in the nozzle and the locator ring, not in any minor exhaust pipe modifications. What is desired is a nozzle design which readily and easily attaches to the vehicle exhaust pipe in a properly aligned fashion. This is where the nozzle locator ring becomes important. Once the nozzle is attached to the locator ring, it is preferred for ambient air to be drawn into the flexible hose of the extraction system when the extraction system exhaust blower is energized. Finally, a quick disconnect between the nozzle and the nozzle locator ring is desired without undue load or stress on any portion of the vehicle or on any portion of the exhaust extraction system. The present invention provides a hose adapter in the style of a flow nozzle which connects to a unique locator ring which is secured to the exhaust pipe. This combination is configured so as to address each of the desired performance criteria in a novel an unobvious way.